CHAPTER XXIV 
THE NEMATOGNATHI, OR CATFISHES 
ic waf/HE Nematognathi—The Nematognatht (vijpa, thread; 
} .* 2 | j yvados, jaw), known collectively as catfishes, are 
+} recognized at once by the fact that the rudimentary 
and usually toothless maxillary is developed as the bony base 
of a long barbel or feeler. Usually other feelers are found around 
the head, suggesting the “smellers’’ of a cat. The body is 
never scaly, being either naked and smooth or else more or less 
completely mailed with bony plates which often resemble 
superficially those of a sturgeon. Other distinctive characters 
are found in the skeleton, notably the absence of the subopercle, 
but the peculiar development of the maxillary and its barbel 
with the absence of scales is always distinctive. The symplectic 
is usually absent, and in some the air-bladder is reduced to a 
rudiment inclosed in a bony capsule. In almost all cases a 
stout spine exists in the front of the dorsal fin and in the front 
of each pectoral fin. This spine, made of modified or coalescent 
soft rays, is often a strong: weapon with serrated edges and 
capable of inflicting a severe wound. When the fish is alarmed, 
it sets this spine by a rotary motion in its socket joint. It can 
then be depressed only by breaking it. By a rotary motion 
upward and toward the body the spine is again lowered. The 
wounds made by this spine are often painful, but this fact is 
due not to a specific poison but to the irregular cut and to the 
slime of the spine. 
In two genera, Noturus and Schilbeodes, a poison-gland exists 
at the base of the pectoral spine, and the wound gives a sharp 
pain like the sting of a hornet and almost exactly like the'sting 
of a scorpion-fish. Most of the Nematognathi possess a fleshy 
or adipose fin behind the dorsal, exactly as in the salmon. In 
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